| T O P I C R E V I E W |
| sqapple |
Posted - 03/29/2011 : 11:35:14 PM
Hi,
The Smoothing dialog provides a drop-down list for defining the boundary condition, to pad the input data so that it have enough data points to calculate the output for the data points near the ends of the data. I learned the Savitzky-Golay algorithm and complete manual computation. To my surprise, the results are the same with the Origin results except for the data points near the ends of the data. When I pad zeros with the ends of data I could not get the same results with the Origin boundary condition "None". May I misunderstood the boundary condition of Origin? I need someone could tell me why.
Here is my example:
I pick the polynomial order 3, and the window size 2*m+1=7 (m=3), so the data after the fourth points are Ok. The data points are:
0.007589
0.007566
0.007596
0.007654
0.00774
0.007883
0.007915
My results of the first fourth data points:
0.0050476
0.0072169
0.0083197
0.0076635
the results from Origin:
0.00759383
0.00755821
0.00758893
0.00766348
Thanks a lot!
Shenqian
|
| 1 L A T E S T R E P L I E S (Newest First) |
| Sam Fang |
Posted - 03/30/2011 : 02:36:35 AM
Origin's S-G smoothing for Boundary Condition "None" doesn't pad zeros at the end of data. It uses Polynomial Fit to calculate smoothed points at the boundary.
Sam
OriginLab Technical Services |
|
|
